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.TH MAHIMAHI 1 "March 2015"
.\" Please adjust this date whenever revising the manpage.
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.SH NAME
\fBmahimahi\fP \- lightweight, composable network-emulation tools

link emulation: \fBmm-delay\fP, \fBmm-loss\fP, \fBmm-onoff\fP, \fBmm-link\fP

analysis scripts: \fBmm-throughput-graph\fP, \fBmm-delay-graph\fP

observation: \fBmm-meter\fP

record and replay multi-origin websites: \fBmm-webrecord\fP, \fBmm-webreplay\fP

.SH DESCRIPTION
\fBmahimahi\fP is a suite of user-space tools for network emulation and analysis.

Each mahimahi tool spawns a lightweight container, generally connected to the
outside via a synthetic network device that observes packets in
transit or emulates a desired behavior.

The tools are composable so that a series of emulated network effects
can be chained together, with mahimahi containers nested inside each
other. Each tool takes an optional command to execute, so it
is possible to create a series of nested containers with one command
line.

.SH LINK EMULATION TOOLS

.SY mm-delay
.I delay
.RI [ command... ]
.YS
.
.IP ""
.RS
Every packet is delayed by the specified
.I delay
(in milliseconds) entering and leaving the container.
.RE

.SY mm-loss
uplink|downlink
.I rate
.RI [ command... ]
.YS
.
.IP ""
.RS

Packets are lost at the given
.I rate
either when leaving (uplink) or entering (downlink) the container.
.I rate
is a number between 0 and 1.
.RE

.SY mm-onoff
uplink|downlink
.I mean-on-time
.I mean-off-time
.RI [ command... ]
.YS
.
.IP ""
.RS

The uplink or downlink will be
intermittent and will switch between connected and disconnected states
according to a Poisson point process with specified average durations
spent "on" and "off".
.RE

.SY mm-link
.OP --uplink-log=\fIfilename\fR
.OP --downlink-log=\fIfilename\fR
.OP --meter-uplink
.OP --meter-uplink-delay
.OP --meter-downlink
.OP --meter-downlink-delay
.OP --once
.I uplink-filename
.I downlink-filename
.RI [ command... ]
.YS
.SY mm-throughput-graph
.SY mm-delay-graph
.YS
.
.IP ""
.RS

Emulates a throughput-limited link with a specified packet-delivery schedule
and analyzes the resulting performance. See
.BR mm-link (1).
.RE

.SH OBSERVATION TOOLS

.SY mm-meter
.OP --meter-uplink
.OP --meter-downlink
.RI [ command... ]
.YS
.
.IP ""
.RS

Displays an animated live plot of the transfer rate entering or leaving the container.
.RE

.SH RECORD AND REPLAY WEBSITES

.SY mm-webrecord
.I directory
.RI [ command... ]
.YS
.
.IP ""
.RS

Transparently proxies outgoing HTTP and HTTPS connections, saving the
requests, corresponding responses, and IP address of each Web
server contacted in the given \fIdirectory\fR. \fBmm-webrecord\fP
uses a self-signed TLS certificate in its HTTPS proxy, causing typical
Web browsers to reject it. For testing or debugging purposes, this
behavior can usually be turned off, e.g.: with the
\fB--no-check-certificate\fP option to
.BR wget (1)
or the \fB--ignore-certificate-errors\fP option to
.BR chromium-browser (1).
.RE

.SY mm-webreplay
.I directory
.RI [ command... ]
.YS
.
.IP ""
.RS

Replays a saved session from a previous run of \fBmm-webrecord\fR.
Unlike most mahimahi tools, the \fBmm-webreplay\fP container
does not have a network connection to the outside world. Instead,
it has dummy network interfaces bound to each IP address on which a
Web server in the saved session had answered a request. \fPmm-webreplay\fR runs an
.BR apache2 (8)
Web server bound to each such IP address inside the container. Each
Web server emulates the corresponding server from the saved
session. When receiving a request that matches one in the \fIdirectory\fR, the
corresponding apache2 replies with the same reply as previously
captured.

\fBmm-webreplay\fP can be used to measure the performance of Web
browsers on complex websites and the effect of changes in Web
protocols (e.g. HTTP, HTTP/2, SPDY, QUIC). Unlike tools like web-page-replay,
\fBmm-webreplay\fP preserves the sharded structure of a website, binds to
the actual IP addresses that the real website used, and serves requests from
real Web servers.
.RE

.SH ENVIRONMENT

The MAHIMAHI_BASE environment variable is set to an IP address of the
host, outside any container. This can be used to conduct scripted
measurements over a series of mahimahi containers chained together.

.SH EXAMPLES

To spawn a shell with a delayed, lossy link to the Internet:

.IP ""
.RS
.EX
\fB$\fR mm-delay 50 mm-loss uplink 0.2
\fB[delay 50 ms] [loss up=0.1] $\fR
.EE
.RE

To run ping over the same link:

.IP ""
.RS
.EX
\fB$\fR mm\-delay 50 mm\-loss uplink 0.2 sh \-c 'ping \-c 10 \-n $MAHIMAHI_BASE'
PING 100.64.0.1 (100.64.0.1) 56(84) bytes of data.
64 bytes from 100.64.0.1: icmp_seq=1 ttl=63 time=101 ms
64 bytes from 100.64.0.1: icmp_seq=2 ttl=63 time=100 ms
64 bytes from 100.64.0.1: icmp_seq=4 ttl=63 time=101 ms
64 bytes from 100.64.0.1: icmp_seq=5 ttl=63 time=100 ms
64 bytes from 100.64.0.1: icmp_seq=7 ttl=63 time=101 ms
64 bytes from 100.64.0.1: icmp_seq=8 ttl=63 time=101 ms
64 bytes from 100.64.0.1: icmp_seq=9 ttl=63 time=101 ms
64 bytes from 100.64.0.1: icmp_seq=10 ttl=63 time=101 ms

--- 100.64.0.1 ping statistics ---
10 packets transmitted, 8 received, 20% packet loss, time 8999ms
rtt min/avg/max/mdev = 100.910/101.009/101.092/0.279 ms
.EE
.RE

To record a page load from \fIwww.nytimes.com\fR:

.IP ""
.RS
.EX
\fB$\fR mm\-webrecord /tmp/nytimes chromium-browser \-\-ignore\-certificate\-errors \-\-user\-data\-dir=/tmp/nonexistent$(date +%s%N) www.nytimes.com
.EE

The use of \fI\-\-user\-data\-dir=/tmp/nonexistent$(date +%s%N)\fR is to prevent the browser from reusing an existing chromium-browser process.
.RE

To make Chrome retrieve the saved website over a delayed, lossy link whose throughput is limited to 1 full-sized packet per millisecond:

.IP ""
.RS
.EX
\fB$\fR mm\-webreplay /tmp/nytimes mm\-delay 50 mm\-loss uplink 0.1 mm-link <(echo 1) <(echo 1) \-\- chromium-browser \-\-ignore\-certificate\-errors \-\-user\-data\-dir=/tmp/nonexistent$(date +%s%N) www.nytimes.com
.EE
.RE

To emulate a variable cellular network and visualize a process's use of the network:

.IP ""
.RS
.EX
\fB$\fR mm\-delay 20 mm\-link \-\-meter-all /usr/share/mahimahi/traces/Verizon-LTE-short.up /usr/share/mahimahi/traces/Verizon-LTE-short.down
\fB[delay 20 ms] [link] $\fR
.EE

.SH SEE ALSO
.BR mm-link (1)

Project home page:
.I http://mahimahi.mit.edu

.br
.SH AUTHOR
Mahimahi was written by Ravi Netravali, Anirudh Sivaraman, Greg D. Hill, Deepak Narayanan, and Keith Winstein.
.SH BUGS
Please report bugs to \fImahimahi@mit.edu\fP.
